¿Por qué el cielo es azul?
01/02/12 21:54 Filed in: Science
Podcast Recommendation
Skeptics Guide to the Universe
A serious problem that we face every day is the fact that it is really difficult to the common person to difference reliable information from bogus one. Everyday we are bombarded with advertisements of magical products that promise to change our lives through: “the power of magnetism”, “ancestral remedies”, “the power of thought”, “balancing energies in our bodies”, “tuning frequencies in our minds”; and many other dubious claims that serve the sole purpose of selling a product. Of course we are also told that these effects have been “scientifically and clinically proven” but are they? This is where the SKGU comes to the rescue.
So what is it?
The SKGU is a weekly podcast that covers topics on sciences and skeptical thinking (yes, I know to most of the people this does not sound exactly appealing nor fun but stay with me). What is really interesting about this podcast and what ultimately sets is apart from other scientific sources for the general public is that not only are the news presented but they are discussed and analyzed through jokes, comparisons and a rigorous scrutiny of their probable truthfulness and the repercussions they can have in society. This is important not only for information purposes but if you constantly listen to their shows you begin to understand the underlying way in which science works and how the media tends to exaggerate research to produce more attractive headlines.
Another thing the SKGU excels at is presenting pseudoscientific claims and explaining how and why are these false along with what kind of emotions are being exploited and the logical fallacies that are taking place whenever these people try to sell their ideas. In my opinion this is the greatest contribution of the podcast as you gradually become less gullible and start to ask yourself the ultimate question: WHY? Why would a magnet cure a disease? Why would a rubber band with a hologram improve my balance? Why do people claim that vaccines are dangerous? And it is through that kind of thinking and constantly asking yourself the reason for everything that you become more than just a consumer of information.
Wrapping up
Either through the witty humor of Bob Novella, Evan Bernstein and Jay Novella; the sarcastic jokes of Rebecca Watson or the fierce defense of the truth of Steven Novella you are guaranteed to have a good time while listening to this podcast (that, as a side note, has won a couple of awards as the best science podcast available) so go on and subscribe to it through iTunes or go to their website on: http://www.theskepticsguide.org/sgu.aspx?MasterPodcastId=1.
P.S. The image of the article is a mammoth using a jetpack (listen to a couple of episodes and you will know what the joke is about).
Sweet dreams…
07/10/11 14:51 Filed in: Medical
Image from: XKCD WebComic
Sleep Paralysis
When we fall asleep our mind usually disconnects our body from our control so that we do not react on our dreams and hurt ourselves. This is a completely natural process and most of us do not notice it. We only notice this process when it is not happening correctly and this failure can result in a very frightening experience.How it manifests…
The usual malfunction goes as follows:
- The person goes to sleep normally and after a while he “wakes up” only to notice he is unable to move or speak.
- Our unfortunate person gets a little anxious and starts to develop a certain sense of “danger”.
- As he is not really awake nor asleep most of the times he gets hallucinations accompanying the attack. These hallucinations are generally perceived as malevolent and although most of the times they are not seen or heard but “felt” some people report being attacked by them (usually felt as exerting pressure in the chest).
- The person awakes suddenly very agitated and most of the times this is when the person realizes it had all been a dream although not everyone makes this connection so easily due to factors as the intensity or the length of the attack.
Who gets it and how to avoid it
People who get these attacks the most are people suffering from narcolepsy but as much as 40% of the general population reports having at least one episode throughout their lives and 15% reports having had episodes throughout their lives so chances are that many of us get at least one of these fun attacks.
There is not a magic cure for these episodes but medics recommend having good sleep hygiene by sleeping at least 6 to 8 hours a day and trying to avoid stressful situations close to bedtime.
Alien abductions, incubi, ghosts
Many scientists believe that most intense hallucinations are related to reports of supernatural encounters of all kinds. Throughout history there have been many mythical figures that appear at night while a person lies immobile for many malignant purposes such as: stealing souls, performing experiments, sexually abusing and many more.
Ok, now I’m scared...
Although a sleep paralysis attack can be a very scary experience there is nothing to worry about as it poses no threat to health. Generally this condition needs no treatment unless a person gets it to frequently and does not get enough sleep because of it. Some people report that the knowledge of this attacks being a “natural” occurrence helps relief the tension whenever one can remember it while having the attack so whenever you wake up being unable to move and feeling that there is a really evil figure watching you remember that it is just your brain malfunctioning.
Sources
http://theness.com/neurologicablog/index.php/sleep-paralysis/http://therapistunlimited.com/rehabs/Articles/Disorders+%26+Disease/Sleep+Paralysis
http://www.stanford.edu/~dement/paralysis.html
http://dreamsnightmares.com/sleepparalysis.html
http://www.webmd.com/sleep-disorders/guide/sleep-paralysis
http://en.wikipedia.org/wiki/Sleep_paralysis
Convolution Madness
Image from: XKCD WebComic
… Or How Some Photoshop Filters Work
Image Processing does involve very complex processes but some filters are not as complex or difficult to program as many of us believe. These filters are mainly created by a mysterious process called: convolution. Yeap, it is a scary word and it is indeed a complex mathematical operation but in mundane words in image processing we use this operation to grab the pixels of an image and modify them according to our needs.Pixels?
Hell yeah! All our digital images are formed by pixels. We can imagine an image to be a two-dimensional grid in which the different squares acquire values that represent the color information of it. So for example in a grayscale image a pixel may acquire the value of 200 and would be whiter than a pixel with a value of 10 (in color images we do not only have one value in an image but three although the principles explained throughout this brief article apply to color images too).The basic idea of a convolution kernel is to center ourselves in any pixel and modify it with relation to the pixels that surround it. One way to do this is to sum all the values of the pixels surrounding our “anchor” pixel and average them out in which case we would be performing a marvelous “Blur” filter.
Kernel?… oh my
The kernel is the one that controls the way we treat the pixels surrounding our anchor pixel. So for example:1/9 - 1/9 - 1/9
1/9 - 1/9 - 1/9
1/9 - 1/9 - 1/9
would multiply the value of every surrounding pixel by 1/9 and then sum all the resulting values. If the value of the pixels was:
10 - 20 - 03
05 - 08 - 16
18 - 17 - 10
our anchor pixel would have the value of 08 the result would be: 1/9*10 + 1/9*20+1/9*03+1/9*05+1/9*08+1/9*16+1/9*18+1/9*17+1/9*10= 12 (roughly); and we would put this value in our anchor pixel in this way:
10 - 20 - 03
05 - 12 - 16
18 - 17 - 10
This procedure would be repeated throughout the image to obtain the desired filter.
Well, maybe we do not want to make blurry images but this principle can be applied to make images sharper if we used another kernel configuration, or we could detect edges, or we could create a filter of our own.
The Demonstration
The following link takes you to a demonstration I created in Mathematica in which you can make your very own 3x3 kernel or modify some existing ones to create your filter. To run the demonstration you need to install a plugin but it takes very little time to do so and could be useful if you like to browse other Mathematica Demonstrations (there are tons of them).
